Re: [PATCH v2 1/2] hwrng: iproc-rng200 - Set the quality value

From: Stefan Wahren <stefan.wahren@i2se.com>
To: "Łukasz Stelmach" <l.stelmach@samsung.com>,
	"Matt Mackall" <mpm@selenic.com>,
	"Herbert Xu" <herbert@gondor.apana.org.au>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Ray Jui" <rjui@broadcom.com>,
	"Scott Branden" <sbranden@broadcom.com>,
	bcm-kernel-feedback-list@broadcom.com,
	"Kukjin Kim" <kgene@kernel.org>,
	"Krzysztof Kozlowski" <krzk@kernel.org>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Markus Elfring" <elfring@users.sourceforge.net>,
	"Matthias Brugger" <mbrugger@suse.com>,
	linux-crypto@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
	"Stephan Mueller" <smueller@chronox.de>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: Re: [PATCH v2 1/2] hwrng: iproc-rng200 - Set the quality value
Date: Thu, 21 May 2020 13:00:33 +0200	[thread overview]
Message-ID: <573b2eff-3c74-90e9-50fa-644264d0a0e5@i2se.com> (raw)
In-Reply-To: <20200519212552.11671-2-l.stelmach@samsung.com>

Hi Lukasz,

Am 19.05.20 um 23:25 schrieb Łukasz Stelmach:
> The value was estimaded with ea_iid[1] using on 10485760 bytes read from
> the RNG via /dev/hwrng. The min-entropy value calculated using the most
> common value estimate (NIST SP 800-90P[2], section 6.3.1) was 7.964464.

could you please mention in the commit the used hardware
implementation(s) of iproc-rng200 to get this quality?

AFAIK there is still no public register description at least for the
bcm2711. So is it safe to assume that the suggested quality applies to
all possible configurations?

Thanks
Stefan

>
> [1] https://github.com/usnistgov/SP800-90B_EntropyAssessment
> [2] https://csrc.nist.gov/publications/detail/sp/800-90b/final
>
> Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
> ---
>  drivers/char/hw_random/iproc-rng200.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/char/hw_random/iproc-rng200.c b/drivers/char/hw_random/iproc-rng200.c
> index 32d9fe61a225..95669ece050f 100644
> --- a/drivers/char/hw_random/iproc-rng200.c
> +++ b/drivers/char/hw_random/iproc-rng200.c
> @@ -199,6 +199,7 @@ static int iproc_rng200_probe(struct platform_device *pdev)
>  	priv->rng.read = iproc_rng200_read,
>  	priv->rng.init = iproc_rng200_init,
>  	priv->rng.cleanup = iproc_rng200_cleanup,
> +	priv->rng.quality = 1000,
>  
>  	/* Register driver */
>  	ret = devm_hwrng_register(dev, &priv->rng);